- My model of MX-5 is: NC
- I’m based near: west kids
- I’m looking for technical help or recommendations on: air cleaner fitment problems
Decided it was time to change the air filter so purchased a branded Bosch filter, made in China…
Removed old filter no problem but new filter was a very tight fit and the bottom locators on the air box would not locate on the front part whatever I tried. Cleaned up old filter and replaced it with no problems. The Bosch filter is a moulded foam type material the old one a paper fibrous material. Anybody else had this problem or is it just me?
Did you notice it has a slightly different shape at one corner, more square than rounded? It’ll only go in one way, difficult to close the box if you’ve got it wrong.
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Tried it both ways but will give it another go, which way should the rounded corner go, the old one seems to fit either way.
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It should be obvious, as the plastic airbox moulding has a rounded corner, which is why it will only go in one way
Have to say, I found it a bit of a fiddle with a Pipercross filter, even when I knew about the rounded corner
I had the whole airbox out last week to do some work on the car. Can’t remember which way that shaped filter goes in but it’s definitely different on one corner to match the corner of the box shape.
Problem appears to be with the height of the folds on the engine side of the filter. The foam type material one “made to exactly fit your car” part from Bosch China is about 3 mm higher than the fibre one currently on the car. As a result the lower edge will not seat correctly as it fouls the filter surface and the rear box will not correctly seat on the front section. I suppose I could trim the folds to fit but that shouldn’t be necessary on a part like this. Will know better next time. Thanks for your advice!
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Have you tried flipping it around?
I mean so the bit that fouls is facing out rather than in?
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Tried that but the wedge shape is even bigger on the other side which just makes the problem worse. You can see the difference on the attached pics.
Wow that is a lot bigger.
Looks like the bosch is not fit for purpose
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Hadn’t read this previously and tried to fit a Bosch filter as described yesterday. In the end gave up and refitted the old filter. Bosch now in the bin, genuine Mazda part ordered.
I fitted the Pipercross filter, then gave that to my Bro-in-law after buying a K&N filter in a sale. Both fitted perfectly and obviously reusable (lifetime for the K&N).
At least someone else has had the same problem. I contacted Bosch aftermarket UK and they promised a Product Manager would look into the problem and contact me. Still waiting though…. Will probably give up and order another make when I do this year’s oil change in a couple of months.
It looks like this squared corners are the problem on the raised parts of the filter. If you notice the chamfered parts of the filter on the right I reckon it’s made like that to contour with the filter box. Try crushing them in a little before fitting.
Alternatively, I’ve always bought the aftermarket filters from Autolink, seem decent quality and fit.
That was my thought as you can see the black witness marks on the filter. I did think about trimming the edges but as the original was in quite good condition I just re fitted it. It’s just annoying that the replacement pattern parts are obviously not the same as the OE parts in some cases.
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I’m sure it must be possible to fit the Bosch filter but it certainly isn’t easy. I’m assuming of course everyone (like me) just unclips the housing and works with limited space available rather than disconnecting the upstream piping?
By the time my hand started bleeding I decided enough was enough.
The Bosch filter is just too bulky/thick, I’m sure aftermarket filters that look more like OEM will fit fine.
Agreed. Life’s too short to fettle a paper air filter. Avoid the Bosch one would be my advice.
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I work in the aftermarket parts and honestly most of these big brands are living off their past names rather than the quality they provide these days.
For reference here’s a pic of the genuine Mazda item. Note the two locating lugs above the writing. I think these help fit the correct way.
Interesting that that one looks nothing like the supposed Bosch alternative.